ata: sata_rcar: drop unused #define's

This driver has never used the SH-Navi2G/ATAPI-ATA compatible taskfile
registers (the driver uses the taskfile registers in another location
anyway), so drop their #define's...

Signed-off-by: Sergey Shtylyov <s.shtylyov@omp.ru>
Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>